Flash Memory Controller NCQ Command Sequencing
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Solution Overview
Problem
The existing flash memory systems face inefficiencies in data writing due to the mismatch between high-speed data transmission connectors and low-speed flash memory programming, leading to prolonged response times for host write commands.
Innovation Solution
Implementing a flash memory controller with a native command queuing (NCQ) protocol that sequences host write commands and data, allowing for simultaneous data transfer and programming through cache program commands, utilizing a microprocessor unit, buffer memory, flash memory interface, host interface, and memory management unit to manage data access efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is transferred through high-speed connectors (e.g., SATA at 1.5 Gb/s or 30 Gb/s), then data transmission speed is improved, but flash memory programming speed remains low causing prolonged response times
Solution Approach 1:
The flash memory controller pre-sequences host write commands using the NCQ protocol before actual data programming begins. By organizing and preparing the command sequence in advance, the controller can efficiently manage the programming process without waiting for each command to be individually processed, thereby reducing the overall response time and better utilizing the high-speed data transmission capability of the connector.
2Reliability
If the flash memory module programs data into memory cells, then data is written to storage, but the flash memory controller cannot process next commands during the programming procedure
Solution Approach 1:
The flash memory controller segments the data writing process into distinct phases: command sequencing phase (using NCQ to organize multiple commands) and execution phase (programming data into memory cells). This segmentation allows the controller to prepare and queue multiple commands in advance, then execute them systematically, improving command processing throughput while ensuring reliable data writing completion.
Solution Approach 2:
The NCQ protocol enables continuous command sequencing and queuing, allowing the flash memory controller to maintain a pipeline of ready-to-execute commands. This continuity ensures that as soon as one programming operation completes, the next command is already prepared and can be immediately executed, maximizing productivity without compromising data writing reliability.
3Measurement precision
If the flash memory controller waits for acknowledgment before processing the next command, then command execution accuracy is maintained, but overall system performance cannot be improved
Solution Approach 1:
The controller performs preliminary command sequencing and validation using the NCQ protocol before execution begins. By pre-organizing the command sequence and verifying its correctness in advance, the controller ensures accurate command execution while reducing the need for repeated acknowledgment waiting, thereby improving overall system performance.
Solution Approach 2:
The NCQ protocol implements a feedback mechanism where the controller sequences commands based on expected acknowledgment patterns and command completion status. This structured feedback approach maintains command execution accuracy by verifying each command's completion while enabling efficient batch processing, thus improving productivity without sacrificing precision.
Data Source
AI summary
A method for giving program commands to a flash memory chip is provided, the method is suitable for writing data from a host system into the flash memory chip. In the present method, a plurality of host write commands and data corresponding to the host write commands are received from the host system by using a native command queuing (NCQ) protocol, and cache program commands are gived to the flash memory chip to write the data into the flash memory chip. Accordingly, the time for executing the host write commands is effectively shortened by writing the data through the cache program commands and the NCQ protocol.